JP2008010059A - Reproducing device and signal quality evaluation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent improper adjustment or the like caused by an erroneous quality measured value. <P>SOLUTION: In the reproducing device corresponding to a recording medium such as an optical disk, to improve the reliability of a quality measured value Eq for evaluating the quality of a signal read from the recording medium, in addition to the quality measured value Eq, a reliability evaluation value Er indicating the reliability of the quality measured value is calculated. The reliability evaluation value Er is used as an index for detecting a state where the quality measured value Eq is not correctly obtained because of poor reproduced signal quality, in other words, an index for determining whether the quality measured value Eq is proper as an index for adjustment or the like. The adequacy of the quality measured value Eq is determined based on the reliability evaluation value Er, and various adjustments are carried out by using the reliability-maintained quality measured value Eq. Thus, reliability of various adjustments using the quality measured value Eq is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a reproducing apparatus that reproduces (or records and reproduces) information on a recording medium on which information is recorded by a sequence of marks and spaces, and a signal quality evaluation method that evaluates the quality of a signal obtained from the recording medium. .

Japanese Patent Laid-Open No. 2004-185796 JP 2003-141823 A Japanese Patent No. 3674160

As a technique for recording / reproducing digital data, for example, there is a data recording technique using an optical disc as a recording medium, such as a CD (Compact Disc) and a DVD (Digital Versatile Disc).
As optical disks, known as CDs, CD-ROMs, DVD-ROMs, etc., read-only types in which information is recorded by embossed pits, CD-Rs, CD-RWs, DVD-Rs, DVDs, etc. There are types in which user data can be recorded as is known in RW, DVD + RW, DVD-RAM, and the like. In the recordable type, data can be recorded by using a magneto-optical recording method, a phase change recording method, a dye film change recording method, or the like. The dye film change recording method is also called a write-once recording method, and can be recorded only once and cannot be rewritten. On the other hand, the magneto-optical recording method and the phase change recording method can rewrite data and are used for various purposes such as recording of various content data such as music, video, games, application programs and the like.
In recent years, a high-density optical disk called a Blu-ray Disc (registered trademark) has been developed, and the capacity has been significantly increased.

  In these optical discs, information is recorded on the disc as embossed pits, pigment change marks, phase change marks, and the like (hereinafter collectively including embossed pits as “marks”). In many cases, the mark on the disc is formed based on a signal obtained by modulating the original data to be recorded into a run-length limited code.

In order to know the performance of a disk drive device (recording device or reproducing device) that performs recording / reproducing with respect to an optical disc, the device itself, an optical head mounted in the device, and an optical disc to be recorded and reproduced. The quality of the reproduced signal is confirmed by measuring the jitter of the reproduced signal.
The jitter here refers to a timing error between the reproduced PLL clock and the waveform edge after binarization of the reproduced signal, and can be measured using, for example, a TIA (Time Interval Analyzer). For example, Patent Document 1 discloses that the average value of the timing error is detected to adjust the recording pulse parameters.
In addition, as described in Patent Documents 2 and 3, an optical disk reproducing apparatus that detects (binarizes) information read from a disk by a maximum likelihood decoding method also uses a suitable index for confirming the quality of a reproduced signal. .
In the following, an evaluation value used for quality confirmation of a signal (reproduction signal) read from these discs is referred to as a “quality measurement value”.

  The above quality measurement values are used for various parameter adjustments for improving the performance of the disk drive device. For example, this quality measurement value is used as an index in order to adjust the recording conditions (e.g., laser light emission pulse width and level) at the time of recording on an optical disk to an optimum state.

However, the quality measurement value has a problem that the reproduction signal quality is worse than expected and the reproduction signal quality cannot be expressed correctly when a timing error exceeding the set window width occurs.
For example, if a data pattern of 2T mark and 3T mark (T is a channel clock period) is recorded longer and the 2T mark is mistakenly decoded into a 3T mark, jitter cannot be detected correctly.

An example in the case where the quality measurement value becomes inappropriate will be described with reference to FIG.
12A, 12B, and 12C, the horizontal axis indicates the mark length of the mark recorded on the disc, and the vertical axis indicates the number of samples (mark appearance number). L2T, L3T, and L4T are ideal values as 2T mark, 3T mark, and 4T mark, respectively.
That is, FIGS. 12A, 12B and 12C show the distribution of mark lengths measured for the marks recorded on the disc.
FIG. 12A shows an appropriate state, and each mark is distributed around the ideal values L2T, L3T, and L4T. The window width W3T shown in the figure is the width of the mark length detected as a 3T mark at the time of reproduction. That is, when a data pattern within the window width W3T is obtained as a reproduction signal at the time of reproduction, it is detected as 3T. In the case of FIG. 12A, however, the mark recorded as 3T is reproduced as 3T.

FIG. 12B shows a case where the recording conditions are not optimal, and the mark length distribution of the recorded marks is broken from an ideal state.
Taking the 3T mark as an example, when such a disc is reproduced, the average value AV3T of the mark length of the 3T mark on the reproduction signal is shifted from the ideal value L3T of the 3T mark. The error between the average value AV3T and the ideal value L3T can be considered to correspond to the timing error described above as an example of the quality measurement value. In this case, the recording condition (laser is set so as to eliminate the error based on the quality measurement value. By adjusting the driving pulse adjustment or the like, the mark to be recorded can be brought close to the state shown in FIG. In other words, in this case, the quality measurement value is correctly used as an index for quality evaluation.

On the other hand, FIG. 12C shows an example in which the quality measurement value is not correct as an index for quality evaluation.
For example, it is assumed that the recording conditions are inappropriate, the 2T mark and 3T mark data patterns are recorded longer, and the marks having the respective mark lengths are distributed as shown in FIG. Then, at the time of reproduction, a longer mark of 2T marks may be erroneously decoded into 3T. This is because the mark recorded as 2T mark includes a mark detected as 3T within the window width W3T.
At this time, when the average value AV3T (S) is considered as the quality measurement value, the average value AV3T (S) becomes a value substantially close to the ideal value L3T.
That is, the average value AV3T (C) of the mark actually recorded as a 3T mark is greatly deviated from the ideal value L3T, but a part of the 2T mark is demodulated as 3T during reproduction, so that the average value AV3T ( S) is calculated. The fact that this average value AV3T (S) is a value that is almost close to the ideal value L3T means that the reproduced signal quality is quite good as a quality measurement value even though the reproduced signal quality is actually quite bad. It becomes that it shows a value. Of course, using such quality measurement values, for example, the recording conditions cannot be adjusted appropriately.

If a value indicating an erroneous determination is generated as a quality measurement value as in this example, an incorrect adjustment is performed when various parameter adjustments are performed based on the quality measurement value. There was a risk of further degrading performance.
Therefore, an object of the present invention is to detect that the reliability of the quality measurement value is lowered in addition to the quality measurement value, and to prevent inappropriate adjustment or the like from being performed.

The reproduction apparatus of the present invention includes a head unit for reading a signal from a recording medium on which information is recorded by a row of marks and spaces, a reproduction process for the signal read by the head unit, and reproduction data. A data reproduction system circuit unit to be obtained, a quality measurement value calculation unit for calculating a quality measurement value indicating the quality of the signal read by the head unit, and a reliability evaluation value indicating the reliability of the quality measurement value A reliability evaluation unit; and a control unit that determines the quality of a signal obtained from the recording medium using the reliability evaluation value and the quality measurement value, and performs predetermined adjustment control based on the determination result.
The reliability evaluation unit calculates a reliability evaluation value by using a decoding result evaluation unit for obtaining a decoding result evaluation value indicating reliability of a decoding result in the data reproduction system circuit unit, and the decoding result evaluation value. An evaluation value calculation unit.
In this case, the decoding result evaluation unit uses the symbol error rate obtained from the error correction processing result at the time of decoding in the data reproduction system circuit unit as the decoding result evaluation value.
Alternatively, the decoding result evaluation unit uses the bit error rate obtained by the bit unit correctness determination for the data obtained by the data reproduction system circuit unit as the decoding result evaluation value.
Alternatively, the decoding result evaluation unit obtains an erroneous recognition rate in the data reproduction system circuit unit for a specific pattern as an information pattern expressed by the mark and space in the recording medium, and determines the erroneous recognition rate as described above. The decryption result evaluation value is used.

In addition, the head unit can record information on the recording medium in a row of marks and spaces, and also provides a recording drive signal based on the data to be recorded to the head unit to execute mark recording on the recording medium. A data recording system circuit unit that controls the recording drive signal using the reliability evaluation value and the quality measurement value.
In this case, the control unit causes the data recording system circuit unit and the head unit to record test recording data on the recording medium while switching the adjustment value of the recording drive signal, and then the head. Unit and the data reproduction system circuit unit execute reproduction of test recording data recorded at each adjustment value, and use the reliability evaluation value and the quality measurement value obtained corresponding to each adjustment value, Adjustment control of the recording drive signal is performed.
The head unit is an optical head unit that irradiates the recording medium with a laser beam to record and read information by a row of marks and spaces, and the data recording system circuit unit performs laser driving as the recording driving signal. A pulse signal is generated, and the control unit performs adjustment control of the edge timing of the laser drive pulse signal as the adjustment control.

  The signal quality evaluation method of the present invention is an adjustment method of a reproducing apparatus for reproducing information on a recording medium on which information is recorded by a mark and space column. A step of calculating a quality measurement value indicating the quality of the read signal, a step of calculating a reliability evaluation value indicating the reliability of the quality measurement value, and the reliability evaluation value. And evaluating the quality of the signal read from the recording medium using the quality measurement value determined to maintain reliability.

  The present invention as described above improves the reliability of the quality measurement value for evaluating the quality of the signal read from the recording medium in a reproducing apparatus corresponding to the recording medium such as an optical disk. For this purpose, in addition to the quality measurement value indicating the reproduction signal quality, a reliability evaluation value indicating the reliability of the quality measurement value is calculated. This reliability evaluation value is an index for detecting a state in which the quality of the reproduced signal is poor and the quality measurement value cannot be acquired correctly, that is, an index for determining whether the quality measurement value is suitable for an index for adjustment or the like. Become. Therefore, it is possible to determine the suitability of the quality measurement value based on the reliability evaluation value, and when the reliability of the quality measurement value is maintained, it is possible to perform various adjustments using the quality measurement value, As a result, it is possible to improve the reliability of various adjustments using the quality measurement value as an index.

An example of the adjustment using the quality measurement value as an index is light strategy adjustment.
In general, in an optical disc recording apparatus, a recording parameter constituting a recording waveform of a laser drive pulse signal is called a write strategy, and information is recorded by causing a laser to emit light based on the write strategy. In recording information on the optical disc, adjusting the write strategy parameter to achieve good recording quality is called write strategy adjustment.
When the reproducing apparatus of the present invention is considered as a recording / reproducing apparatus having a function of recording information on a recording medium, a data recording system circuit unit generates a laser driving pulse signal based on recording data, and a head unit generates a laser driving pulse. Recording is performed by laser irradiation based on the signal, but it is necessary to appropriately adjust the pulse width and edge timing (write strategy adjustment) of the waveform of the laser drive pulse signal. In write strategy adjustment, test recording is performed while changing adjustment values such as edge timing. Then, they are reproduced to detect a quality measurement value in the case of each adjustment value, and determine an adjustment value that provides an optimum quality measurement value. Then, an optimum adjustment value is set. Here, when a certain adjustment value is set in the test recording, if it is far away from the optimum value, the quality of the mark recorded in the test recording becomes very bad, so the mark length is decoded erroneously. For example, quality measurement values may not be acquired correctly. For example, a quality measurement value may erroneously become a value that indicates very good quality. As a result, erroneous write strategy adjustment is performed, but in the present invention, such erroneous quality measurement values can be eliminated by the reliability evaluation value.
In this specification, the “decoding result” means a binarization result before error correction processing or the like is performed in the data reproduction process.

According to the present invention, when evaluating the quality of a signal reproduced from a recording medium, a reliability evaluation value is used in addition to a quality measurement value indicating the signal quality. By detecting that the reliability of the quality measurement value has decreased due to the reliability evaluation value, it is possible to evaluate the signal quality by appropriately using the quality measurement value. For example, when the quality measurement value becomes an incorrect value, the quality measurement value can be prevented from being used for signal quality evaluation.
And, the quality measurement value can be used appropriately to evaluate the signal quality. This means that when making various parameter adjustments such as light strategy adjustment while evaluating the signal quality using the quality measurement value, it is highly reliable adjustment. Can be realized. For this reason, it is possible to improve the operation performance of the reproducing apparatus (recording / reproducing apparatus).

Hereinafter, a disk drive apparatus (recording / reproducing apparatus) that performs recording / reproducing with respect to an optical disk and its operation will be described as embodiments of the reproducing apparatus and signal quality evaluation method of the present invention. The description will be given in the following order.
[1. Configuration concept of embodiment]
[2. Configuration of disk drive unit]
[3. Light strategy adjustment using quality measurements and reliability evaluation values]

[1. Configuration concept of embodiment]

The specific configuration and operation of the disk drive device will be described later with reference to FIGS. 7 to 11. First, the configuration concept as an embodiment of the present invention will be described with reference to FIGS. .
FIG. 1 shows a basic configuration of the embodiment.

FIG. 1 is a block diagram schematically showing a configuration concept of a disk drive device according to an embodiment. A head unit 30, a data reproduction system circuit unit 31, a data recording system circuit unit 32, a control unit 33, and a quality evaluation unit 20 are illustrated. The structure which has is shown.
The head unit 30 irradiates a disk 90 on which information is recorded with rows of marks and spaces with laser light, and reads and records information.
The data reproduction system circuit unit 31 performs reproduction processing on the signal read by the head unit 30 to obtain reproduction data DP. For example, the RF signal (reproduction data signal) read by the head unit 30 is converted into digital data by A / D conversion. Also, a reproduction clock for A / D conversion and decoding is generated by a PLL circuit. Then, the digitalized signal is decoded into binary data. Further, the reproduction data Dp is obtained by performing binarized data decoding processing, error correction processing, deinterleaving and the like.
The data recording system circuit unit 32 applies a laser driving pulse signal to the head unit as a recording driving signal based on the data to be recorded, and executes laser beam irradiation to execute mark recording on the disk 90. For example, the data recording system circuit unit 32 performs interleaving, error correction code addition, encoding processing for recording, and the like on the data to be recorded. Then, a laser driving pulse signal is generated according to the data encoded for recording, and supplied to the head unit 30 to execute laser output.

The quality evaluation unit 20 includes a quality measurement value calculation unit 21 and a reliability evaluation unit 22.
The quality measurement value calculation unit 21 calculates a quality measurement value Eq indicating the quality of the signal read by the head unit 30 and processed by the data reproduction system circuit unit 31.
The reliability evaluation unit 22 calculates a reliability evaluation value Er indicating the reliability of the quality measurement value Eq.
The quality measurement value Eq and the reliability evaluation value Er are supplied to the control unit 33.
The control unit 33 determines the quality of the signal obtained from the disk 90 using the quality measurement value Eq and the reliability evaluation value Er, and performs predetermined adjustment control based on the determination result.

The quality measurement value Eq itself is a value (for example, jitter value) indicating the quality of the signal, and the control unit 33 can evaluate the signal quality by the quality measurement value Eq. Therefore, when performing various parameter adjustments, adjustments may be made so as to obtain a signal with the best quality measurement value Eq. However, in this example, the control unit 33 evaluates the supplied quality measurement value Eq with the reliability evaluation value Er. For example, the quality measurement value Eq that can be determined to be “unreliable” based on the reliability evaluation value Er is not used as an index for parameter adjustment.
By performing such processing, it is possible to determine the signal quality using only the correct quality measurement value Eq, and to correctly perform parameter adjustment based on the determination.

Configuration examples of the reliability evaluation unit 22 are shown in FIGS. 2 to 5, the same parts as those in FIG.
FIG. 2 shows an example in which the reliability evaluation unit 22 includes a decryption result evaluation unit 24 and an evaluation value calculation unit 23.
The decoding result evaluation unit 24 obtains a decoding result evaluation value indicating the reliability of the decoding result (binarization result) in the data reproduction system circuit unit 31.
The evaluation value calculation unit 23 calculates the reliability evaluation value Er using the decoding result evaluation value obtained by the decoding result evaluation unit 24.

More specific examples of the decoding result evaluation unit 24 are shown in FIGS.
FIG. 3 shows an example in which the decoding result evaluation unit 24 is configured by a SER (symbol error rate) calculation unit 24a.
The data reproduction system circuit unit 31 performs error correction processing in units of ECC blocks during the decoding process. In this case, the number of bytes-level errors can be known in units of ECC blocks. The SER calculation unit 24a acquires such a symbol error rate. The symbol error rate is an error rate of the decoding result, and is an evaluation index of the decoding result. This can be an indicator of signal quality, but can also be an indicator of the reliability of the quality measurement value Eq.
Therefore, the evaluation value calculation unit 23 can generate the reliability evaluation value Er based on the symbol error rate.

FIG. 4 shows an example in which the decoding result evaluation unit 24 is configured by a bER (bit error rate) calculation unit 24b.
The bit error rate is a mistake rate of the decoding result obtained by comparing the reproduction data with the original recording data of the reproduction data in bit units.
In this case, test recording data is generated from the test recording data generation unit 34 as shown in the figure, and is recorded on the disk 90 by the head unit 30 through the processing of the data recording system circuit unit 32. Thereafter, when the recorded data is reproduced, the bER calculation unit takes in the reproduction data obtained by the data reproduction system circuit unit 31 and compares it with the test recording data bit by bit to determine whether the data is correct. Then, a bit error rate is obtained from the correctness determination result of each bit.
This bit error rate also becomes an evaluation index of the decoding result, and particularly reflects the error rate of the decoding result. This can also be used as an index of the reliability of the quality measurement value Eq. Therefore, the evaluation value calculation unit 23 can generate the reliability evaluation value Er based on the bit error rate.

FIG. 5 shows an example in which the decoding result evaluation unit 24 includes a pattern-specific sample number integrator 24c and an erroneous recognition rate calculation unit 24d.
The pattern-specific sample number accumulator 24c accumulates the number of samples for a specific pattern, for example, a 2T pattern, a 3T pattern, or the like, as a pattern of information expressed by marks and spaces on the disk 90. That is, every time a 2T pattern, 3T pattern, or the like is detected in a binarized reproduction signal, the number of samples is counted.
The misrecognition rate calculation unit 24d calculates the misrecognition rate for each pattern obtained by accumulating the number of samples based on the ratio between the number of samples that should be originally obtained during reproduction and the number of samples actually counted.
For example, the number of samples that should be obtained can be determined for each pattern if the recorded data at the time of test recording is known. For example, if random data is recorded, The number of occurrences may be estimated from a general occurrence frequency.
The error recognition rate almost reflects the error rate of the decoding result, and can therefore be used as an index of the reliability of the quality measurement value Eq. Therefore, the evaluation value calculation unit 23 can generate the reliability evaluation value Er based on the erroneous recognition rate.
The configuration of FIG. 5 has an advantage that the decoding result evaluation unit 24 can relatively easily make a circuit as compared with the configuration of FIG.

  The pattern-specific number of samples may be classified for each mark length (2T mark, 3T mark, 4T mark, etc.), or a classification including the immediately preceding space length, mark length, and immediately following space length, For example, “2T space, 2T mark, xT space”, “3T space, 2T mark, xT space”,..., “XT space, 4T mark, 5T space” may be used. In addition, xT space shows the space of arbitrary length.

For example, the configuration example of the quality evaluation unit 20 is considered as described above, but the configuration example in which the control unit 33 performs adjustment using the quality measurement value Eq and the reliability evaluation value Er generated by the quality evaluation unit 20 is shown in FIG. Shown in This is a configuration example in which, for example, write strategy adjustment is performed.
As the write strategy adjustment, the control unit 33 determines the processing function as the recording pulse shift setting unit 33a for changing the edge timing and the pulse width as parameters of the laser drive pulse signal, and the adjustment value as the optimum write strategy, and finally In particular, it has a processing function as a write strategy calculation unit that sets the adjustment value.
The detailed operation of the write strategy adjustment will be described later. For example, in the configuration of FIG. 6, the control unit generates test recording data from the test recording data generation unit 34, and changes the adjustment value by the function of the recording pulse shift setting unit 33a. The test recording data is recorded a plurality of times. That is, the test recording data is recorded on the disk 90 a plurality of times with different write strategies (different adjustment values).
Then, by reproducing the data recorded in this way and obtaining the quality measurement value Eq and the reliability evaluation value Er for each write strategy, the write strategy calculation unit 33b of the control unit 33 allows the optimum write strategy (adjustment value). Determine. For example, among the quality measurement values Eq and the reliability evaluation values Er obtained corresponding to the respective adjustment values, the quality measurement values Eq that are determined to have low reliability by the reliability evaluation values Er are excluded. Then, the remaining quality measurement value Eq, that is, the quality measurement value Eq that can be determined to be reliable, is selected as the optimum quality, and the adjustment value corresponding to the optimum quality measurement value Eq is selected. The optimum adjustment value (optimum write strategy) is set, and adjustment control is performed to the optimum adjustment value.

1 to 6, the quality evaluation unit 20 is shown as a block different from the control unit 33. However, the quality evaluation unit 20 and the control unit 33 are actually realized by a single microcomputer. You can also

[2. Configuration of disk drive unit]

In the following, as a more specific embodiment, a disk drive device that can perform reproduction and recording in correspondence with a reproduction-only disc or a recordable disc (a write-once disc or a rewritable disc) corresponding to a Blu-ray disc is taken as an example. Will be described.

In the case of a recordable disc of the Blu-ray Disc system, recording / reproducing of a phase change mark (phase change mark) and a dye change mark is performed under the condition of a combination of a laser having a wavelength of 405 nm (so-called blue laser) and an objective lens having an NA of 0.85 Recording / reproduction is performed using a data block of 64 KB (kilobytes) as a single recording / reproducing unit (RUB) at a track pitch of 0.32 μm and a linear density of 0.12 μm / bit.
For the ROM disk, reproduction-only data is recorded by embossed pits having a depth of about λ / 4. Similarly, the track pitch is 0.32 μm and the linear density is 0.12 μm / bit. A 64 KB data block is handled as one reproduction unit (RUB).

The RUB, which is a recording / playback unit, is a total of 498 frames generated by adding a link area of one frame before and after, for example, an ECC block (cluster) of 156 symbols × 496 frames.
In the case of a recordable disc, a groove (groove) is formed on the disc by meandering (wobbling), and this wobbling groove is used as a recording / reproducing track. Groove wobbling includes so-called ADIP (Address in Pregroove) data. In other words, the address on the disk can be obtained by detecting the wobbling information of the groove.

In the case of a recordable disc, a recording mark by a phase change mark is recorded on a track formed by a wobbling groove, but the phase change mark is an RLL (1, 7) PP modulation method (RLL; Run Length Limited, PP). : Parity preserve / Prohibit rmtr (repeated minimum transition runlength)), etc., with linear densities of 0.12 μm / bit and 0.08 μm / ch bit.
When the channel clock period is “T”, the mark length is 2T to 8T. That is, the shortest code is 2T and the longest code is 8T.
In the case of a read-only disc, no groove is formed, but similarly data modulated by the RLL (1, 7) PP modulation method is recorded as an embossed pit row.

FIG. 7 shows a disk drive device capable of recording / reproducing corresponding to such a disk.
The disc 90 is, for example, the above-described Blu-ray disc type read-only disc or recordable disc.
When the disk 90 is loaded into the disk drive device, it is loaded on a turntable (not shown), and is rotationally driven by the spindle motor 2 at a constant linear velocity (CLV) during recording / reproducing operations.
During reproduction, information of marks (pits) recorded on tracks on the disk 90 is read by the optical pickup (optical head) 1.
When the disk 90 is a recordable disk, the user data is recorded as a phase change mark or a dye change mark on a track on the disk 90 by the optical pickup 1 at the time of data recording.
On the disc 90, for example, physical information of the disc is recorded as reproduction-only management information by embossed pits or wobbling grooves. Reading of these information is also performed by the pickup 1. Further, the ADIP information embedded as wobbling of the groove track on the disk 90 is also read from the recordable disk 90 by the optical pickup 1.

In the pickup 1, a laser diode serving as a laser light source, a photodetector for detecting reflected light, an objective lens serving as an output end of the laser light, and a laser recording light are irradiated onto the disk recording surface via the objective lens. An optical system or the like for guiding the reflected light to the photodetector is formed. The laser diode outputs, for example, a so-called blue laser having a wavelength of 405 nm. The NA by the optical system is 0.85.
In the pickup 1, the objective lens is held so as to be movable in the tracking direction and the focus direction by a biaxial mechanism.
The entire pickup 1 can be moved in the disk radial direction by the thread mechanism 3.
The laser diode in the pickup 1 is driven to emit laser light by a drive signal (drive current) from the laser driver 13.

Reflected light information from the disk 90 is detected by a photo detector, converted into an electrical signal corresponding to the amount of received light, and supplied to the matrix circuit 4.
The matrix circuit 4 includes a current-voltage conversion circuit, a matrix calculation / amplification circuit, and the like corresponding to output currents from a plurality of light receiving elements as photodetectors, and generates necessary signals by matrix calculation processing.
For example, a reproduction RF signal corresponding to reproduction data, a focus error signal for servo control, a tracking error signal, and the like are generated.
Further, a push-pull signal is generated as a signal related to groove wobbling, that is, a signal for detecting wobbling.
The reproduction RF signal output from the matrix circuit 4 is supplied to the A / D / PLL unit 5, the focus error signal and tracking error signal are supplied to the optical block servo circuit 11, and the push-pull signal is supplied to the wobble decoder 15.

  The A / D / PLL unit 5 includes an A / D conversion circuit and a PLL circuit, and converts a reproduction RF signal, which is an analog signal, into digital data. The output Drd of the A / D conversion circuit is supplied to the reproduction processing unit 6 at the subsequent stage and is also supplied to the PLL circuit, and the clock CK used for the reproduction processing is reproduced by the phase locked loop. The generated clock CK is used as a sampling clock for the A / D conversion circuit and used for decoding processing in the reproduction processing unit 6.

The reproduction processing unit performs binarization decoding processing on the reproduced RF signal read from the disk 90 and digitized, and performs decoding processing, error correction processing, and the like on the obtained binary data string to reproduce the reproduction data. Get Dp.
First, as binarization processing, for example, PR (Partial Response) equalization processing and Viterbi decoding (maximum likelihood decoding) processing are performed. That is, a binary data string is obtained by a partial response maximum likelihood decoding process (PRML detection method: Partial Response Maximum Likelihood detection method).
The binary data sequence obtained by using the partial response maximum likelihood detection method is subjected to RLL (1, 7) PP modulation and data recorded on the disk 90 by demodulation processing, deinterleaving, The reproduction data Dp from the disk 90 is demodulated by performing ECC decoding processing for error correction.

  Data demodulated as reproduction data Dp by the reproduction processing unit 6 is transferred to the host interface 8 and transferred to the host device 100 based on an instruction from the system controller 10. The host device 100 is, for example, a computer device or an AV (Audio-Visual) system device.

If the disc 90 is a recordable disc, ADIP information processing is performed during recording / reproduction.
That is, the push-pull signal output from the matrix circuit 4 as a signal related to the wobbling of the groove is supplied to the wobble decoder 15 and the ADIP information is decoded. In this case, a clock synchronized with the push-pull signal is generated, and the push-pull signal is converted into digital data. Then, MSK demodulation and STW demodulation are performed to demodulate a data string constituting the ADIP address. This data string is decoded, and ADIP information such as an address value is demodulated. The demodulated ADIP information is supplied to the system controller 10.

During recording, recording data is transferred from the host device 100, and the recording data is supplied to the recording processing unit 7 via the host interface 8.
The recording processing unit 7 performs error correction code addition (ECC encoding), interleaving, subcode addition, and the like as recording data encoding processing. Further, RLL (1-7) PP modulation is performed on the data subjected to these processes.

The recording data processed by the recording processing unit 7 is subjected to a recording compensation process in the write strategy unit 14 for fine adjustment of optimum recording power and laser drive pulse waveform for recording layer characteristics, laser beam spot shape, recording linear velocity, etc. The laser drive pulse signal in a state where the adjustment is performed is supplied to the laser driver 13. The laser driving pulse signal waveform is adjusted based on an instruction from the system controller 10.
Then, the laser driver 13 supplies the laser driving pulse signal subjected to the recording compensation process to the laser diode in the pickup 1 to execute the laser emission driving. As a result, a mark corresponding to the recording data is formed on the disk 90.
The laser driver 13 includes a so-called APC circuit (Auto Power Control), and the laser output is not dependent on temperature or the like while monitoring the laser output power by the output of the laser power monitoring detector provided in the pickup 1. Control to be constant. The target value of the laser output at the time of recording and reproduction is given from the system controller 10, and the laser output level is controlled to be the target value at the time of recording and reproduction.

The optical block servo circuit 11 generates various servo drive signals for focus, tracking, and thread from the focus error signal and tracking error signal from the matrix circuit 4 and executes the servo operation.
That is, a focus drive signal and a tracking drive signal are generated according to the focus error signal and tracking error signal, and the biaxial driver 18 drives the focus coil and tracking coil of the biaxial mechanism in the pickup 1. As a result, the pickup 1, the matrix circuit 4, the optical block servo circuit 11, the biaxial driver 18, the tracking servo loop and the focus servo loop by the biaxial mechanism are formed.
The optical block servo circuit 11 turns off the tracking servo loop in response to a track jump command from the system controller 10 and outputs a jump drive signal to execute a track jump operation.
The optical block servo circuit 11 generates a thread drive signal based on a thread error signal obtained as a low frequency component of the tracking error signal, access execution control from the system controller 10, and the like. To drive. Although not shown, the thread mechanism 3 includes a mechanism including a main shaft that holds the pickup 1, a thread motor, a transmission gear, and the like, and a required slide of the pickup 1 by driving the thread motor in accordance with a thread drive signal. Movement is performed.

The spindle servo circuit 12 performs control to rotate the spindle motor 2 at CLV.
The spindle servo circuit 12 obtains the clock generated by the PLL processing for the wobble signal as the current rotational speed information of the spindle motor 2, and compares it with predetermined CLV reference speed information to generate a spindle error signal. .
Further, at the time of data reproduction, the reproduction clock generated by the PLL in the data signal processing circuit 5 becomes the current rotational speed information of the spindle motor 2, so that the spindle is compared with predetermined CLV reference speed information. An error signal can also be generated.
The spindle servo circuit 12 outputs a spindle drive signal generated according to the spindle error signal, and causes the spindle driver 17 to execute CLV rotation of the spindle motor 2.
Further, the spindle servo circuit 12 generates a spindle drive signal in response to a spindle kick / brake control signal from the system controller 10, and also executes operations such as starting, stopping, acceleration, and deceleration of the spindle motor 2.

Various operations of the servo system and the recording / reproducing system as described above are controlled by a system controller 10 formed by a microcomputer.
The system controller 10 executes various processes in accordance with commands from the host device 100 given through the host interface 8.
For example, when a write command (write command) is issued from the host device 100, the system controller 10 first moves the pickup 1 to an address to be written. Then, the recording processing unit 7 causes the encoding process to be executed as described above for data transferred from the host device 100 (for example, video data, audio data, etc.). Recording is executed by the laser driver 13 driving to emit laser light in accordance with the encoded data as described above.

Further, for example, when a read command for requesting transfer of certain data recorded on the disk 90 is supplied from the host device 100, the system controller 10 first performs seek operation control for the instructed address. That is, a command is issued to the optical block servo circuit 11, and the access operation of the pickup 1 targeting the address specified by the seek command is executed.
Thereafter, operation control necessary for transferring the data in the designated data section to the host device 100 is performed. That is, data is read from the disk 90, the reproduction processing in the reproduction processing unit 6 is executed, and the requested data is transferred.

  The memory unit 9 stores program codes executed in the system controller 10 (microcomputer), is used for temporarily storing work data being executed, various management information read from the disk 90, physical information, etc. In this figure, the memory unit 9 is shown as including both a volatile memory and a non-volatile memory. For example, ROM (Read Only Memory) for storing programs, RAM (Random Access Memory) for temporary storage of calculation work areas and various information, and nonvolatile memories such as EEPROM-Electrically Erasable and Programmable Read Only Memory (ROM) .

  Further, an example of performing test recording in the write strategy adjustment will be described later. When a fixed data pattern is used as test recording data to be recorded at that time, data as the test recording data is stored in the memory unit 9. It may be. When a random pattern is used as test recording data, the system controller 10 may be provided with a random data generation function.

The quality evaluation unit 20 includes a quality measurement value calculation unit 21 and a reliability evaluation unit 22.
The quality measurement value calculation unit 21 calculates a quality measurement value Eq indicating the quality of the signal processed by the reproduction processing unit 6.
The reliability evaluation unit 22 calculates a reliability evaluation value Er indicating the reliability of the quality measurement value Eq.
The quality measurement value Eq and the reliability evaluation value Er are supplied to the control unit 33.
As an example of the configuration of the quality evaluation unit 20, the examples described in FIGS. 1 to 5 are assumed.
In the figure, the quality evaluation unit 20 is shown as a block different from the system controller 10, but the quality evaluation unit 20 can also be realized by a software operation function in the system controller 10.
The system controller 10 can determine the quality of the signal obtained from the disk 90 using the quality measurement value Eq and the reliability evaluation value Er, and can perform predetermined adjustment control based on the determination result.

The components in the configuration concept described in FIGS. 1 to 6 and the configuration example in FIG. 7 can be considered to correspond, for example, as follows.
Head unit 30: pickup 1 and matrix circuit 4
Data reproduction system circuit unit 31: A / D / PLL unit 5 and reproduction processing unit 6
Data recording system circuit unit 32: recording processing unit 7, write strategy 14, and laser driver 13
Control unit 33: system controller 10 and memory unit 9
Test record data generation unit 34: system controller 10 and memory unit 9

Although the example of FIG. 7 has been described as a disk drive device connected to the host device 100, the disk drive device of the present invention may have a form that is not connected to other devices. In that case, an operation unit and a display unit are provided, and the configuration of the interface part for data input / output is different from that in FIG. That is, it is only necessary that recording and reproduction are performed in accordance with a user operation and a terminal unit for inputting / outputting various data is formed.
Of course, various other examples of the configuration of the disk drive device are conceivable. For example, an example of a read-only device is also conceivable.

[3. Light strategy adjustment using quality measurements and reliability evaluation values]

In such a disk drive device, an example will be described in which write strategy adjustment is performed as an example of processing for determining reproduction signal quality using the quality measurement value Eq and reliability evaluation value Er and performing predetermined adjustment. That is, this is an example of an operation realized with the configuration described in FIG. 6, and the system controller 10 is provided with the functions of the recording pulse shift setting unit 33a and the write strategy calculation unit 33b in FIG. Based on these functions, the system controller 10 controls the processing of FIG.
As shown in FIGS. 5 and 6, the quality evaluation unit 20 has a configuration in which the reliability evaluation unit 22 includes a pattern-specific sample number integrator 24 c, an erroneous recognition rate calculation unit 24 d, and an evaluation value calculation unit 23. Will be described.

As described above, in the optical disk drive device, the recording parameter constituting the laser recording waveform is called a write strategy, and information (marks) is recorded on the disk 90 by causing the laser to emit light based on this write strategy. Is done. In recording information on the disc 90, adjusting the write strategy parameter to achieve good recording quality is called write strategy adjustment.
A basic strategy setting used as a reference when performing such a write strategy adjustment is referred to as a “reference strategy”.
In this example, the write strategy adjustment is performed by correcting the reference strategy. As specific setting values, setting values determined by the disk manufacturer (setting values recorded on the disk 90), strategy setting values stored in advance by the disk drive device, and the like are used as reference strategies.
In addition, as an example of the write strategy adjustment, an adjustment for shifting the front edge and the rear edge of the laser drive pulse signal is performed.
For example, in the laser drive pulse signal as shown in FIG. 11, the front edge EF and the rear edge ER are pulse edges as shown in the figure. However, this is only an example. In practice, the pulse edge on the laser drive pulse signal that can effectively adjust the front edge (mark leading edge position) and rear edge (mark trailing edge position) of the generated mark is matched to the media type. It is preferable to select them.
In the write strategy adjustment of this example, one or both of the front edge EF and rear edge ER in the laser drive pulse signal for forming a predetermined mark length is shifted in the arrow Z direction, and laser drive for the mark length is performed. It is assumed that test recording is performed while changing the signal width WS (hereinafter, recording pulse width) of the pulse signal.

The write strategy adjustment process will be described with reference to FIG.
First, in the loop processing as Steps F101 to F105 in FIG. 8, test recording with each adjustment value (write strategy), and quality measurement value Eq and reliability for signal quality evaluation by reproducing the test recorded data Processing for obtaining the evaluation value Er is performed. The loop is an example in which the loop control variable i is performed 81 times from i = 0 to 80.

In step F101, the system controller 10 performs a shift setting of the recording pulse width WS of the laser drive pulse signal for the 2T mark and the 3T mark as the write strategy adjustment value.
Performing the test recording loop 81 times as described above means that the test recording data is recorded with 81 adjustment values (write strategies). The 81 adjustment values are, for example, P0 to P80 in FIG.
In FIG. 9, with the adjustment value P0 as the origin, the pulse width of the laser drive pulse signal for the 2T mark and the pulse width of the laser drive pulse signal for the 3T mark are shifted by the front edge EF and the rear edge ER. Each adjustment value P0 to P80 is shown as being variably set in increments of 1 [nsec] within a range of ± 4 [nsec].
The adjustment value P0 is a set value of the recording pulse width as the reference strategy. For example, the adjustment value P1 indicates an adjustment value for setting the recording pulse width of the 2T mark to +4 [nsec] and the recording pulse width of the 3T mark to +4 [nsec] from the reference strategy. The adjustment value P2 indicates an adjustment value that sets the recording pulse width of the 2T mark to +4 [nsec] and the recording pulse width of the 3T mark to +3 [nsec] from the reference strategy. Similarly, as adjustment values P3 to P80, adjustment values for variably setting the recording pulse widths of the 2T mark and the 3T mark are determined from the reference strategy.
The adjustment value for shifting the recording pulse width by X [nsec] means that the front edge EF and rear edge ER of the laser driving pulse signal are shifted by −X / 2 [nsec] and + X / 2 [nsec], respectively. It can be considered as an adjustment value to be instructed.

For such 81 adjustment values, for example, in the first loop processing (i = 0), the system controller 10 selects the adjustment value P0 as the reference strategy in step F101, and this adjustment value P0 is used as the write strategy. The unit 14 is instructed.
In step F102, test recording is executed. That is, the system controller 10 supplies the test recording data to the recording processing unit 7 and causes the recording processing unit 7 to execute an encoding process at the time of recording. The encoded test recording data is used as a laser driving pulse signal whose waveform is adjusted by the adjustment value P0 in the write strategy unit 14, and the laser driver 13 performs laser light emission driving of the pickup 1 by the laser driving pulse signal. A mark / space sequence based on test recording data is recorded on the disk 90.

The test recording data may be a fixed data pattern including, for example, 2T to 8T patterns at random, or may be a random data pattern generated at the time of test recording.
When a fixed data pattern is used, the same pattern data is recorded in all 81 test recordings. On the other hand, in the case of a random data pattern, a total of 81 test recordings record different patterns of data, but such test recording may be performed.
However, as described with reference to FIG. 5, when the reliability evaluation value Er is generated based on the erroneous recognition rate of the number of samples by pattern, the accuracy of the reliability evaluation value Er is higher when the fixed data pattern is used.

When the first test recording is performed as described above, the quality measurement value Eq is measured in step F103. In step F104, a reliability evaluation value for decoding results is obtained, and a reliability evaluation value Er is calculated in step F105.
That is, in steps F103, F104, and F105, the system controller 10 causes the pickup 1 to read out test recording data from the disk 90, causes the reproduction processing unit 6 to decode the reproduction data DP, and performs a quality evaluation unit. The quality measurement value Eq is calculated by the quality measurement value calculation unit 21 of 20, and the quality measurement value Eq is captured.
Also, the decoding result reliability evaluation value as the error recognition rate is given to the decoding result evaluation unit 24 (the sample-by-pattern integrator 24c and the error recognition rate calculation unit 24d in FIG. 5) in the reliability evaluation unit 22 of the quality evaluation unit 20. Further, the evaluation value calculation unit 23 calculates the reliability evaluation value Er based on the misrecognition rate, and takes in the reliability evaluation value Er.
An example of a method for calculating the quality measurement value Eq and the reliability evaluation value Er will be described later.
The system controller 10 stores the quality measurement value Eq and the reliability evaluation value Er thus captured in the memory unit 9 in association with the adjustment value P0.

Subsequently, the second test recording and reproduction are performed.
For example, at the second loop processing (i = 1), the system controller 10 selects the adjustment value P1 as a strategy and instructs the write strategy unit 14 of this adjustment value P1.
Then, the test recording in step F102 is performed in the same manner as described above, the recorded data is reproduced, the quality measurement value Eq and the reliability evaluation value Er are calculated in steps F103, F104, and F105, and the acquired quality measurement value Eq and reliability are calculated. The evaluation value Er is stored in the memory unit 9 in association with the adjustment value P1.

  Such test recording, quality measurement value Eq and reliability evaluation value Er are taken in for adjustment values P2 to P80 in the same manner. Then, when the loop processing of 81 times is completed, the quality measurement value Eq and the reliability evaluation value Er are captured corresponding to each of the adjustment values P0 to P80.

When the above loop processing is completed, the system controller 10 determines an optimum write strategy (adjustment value) from the test recording result in step F106.
At this time, the quality measurement value Eq and the reliability evaluation value Er are stored for each of the adjustment values P0 to P80. As a process for determining the optimum adjustment value, for example, the quality measurement value Eq is first selected with reference to the reliability evaluation value Er. Specifically, as the value of the reliability evaluation value Er, the quality measurement value Eq that is a value at which it can be determined that “reliability cannot be guaranteed” is excluded. That is, a predetermined threshold value is set as the reliability evaluation value Er, the reliability evaluation value Er is selected based on the threshold value, and those with low reliability are excluded.
Then, among the quality measurement values Eq that are not excluded from the reliability evaluation value Er, the one having the best quality measurement value Eq is selected and corresponds to the selected quality measurement value Eq. The adjustment value P (x) to be determined is determined as the optimum write strategy.

Various methods for determining the actual optimum adjustment value are conceivable. For example, when an optimum adjustment value is selected from among adjustment values that are not excluded from the reliability evaluation value Er, not only the quality measurement value Eq but also the reliability evaluation value Er is taken into consideration. Processing such as selection is also conceivable.
For example, when there are a plurality of quality measurement values Eq having the best value, an adjustment value having the best reliability evaluation value Er is selected, or the quality measurement value Eq and the reliability evaluation value are selected. For example, a calculation is performed such that each Er is multiplied by a predetermined coefficient and added, and an adjustment value that gives the best calculation result is selected.

In step F107, the optimum adjustment value P (x) determined in step F106 is instructed to the write strategy unit 14, and thereafter, the laser strategy pulse signal waveform is shaped with the adjustment value P (x) in the write strategy unit 14. To be.
This completes the write strategy adjustment.

  An example of a quality measurement value Eq calculation method performed by the quality measurement value calculation unit 21 as Step F103 and a reliability evaluation value Er calculation method performed by the reliability evaluation unit 22 as Steps F104 and F105 will be described. .

The quality measurement value calculation unit 21 calculates the quality measurement value Eq from the error from the ideal value of the average mark length width after binarization of the reproduction signal.
First, as shown in FIG. 10, the binarized mark length width of each of the 2T mark and the 3T mark is set to w2Tm and w3Tm [nsec]. FIG. 10A shows 3T marks and 2T marks as marks recorded on the disk 90, and FIG. 10B shows a reproduction RF signal waveform read from the mark row. FIG. 10C shows a binarized signal binarized by the reproduction processing unit 6. The mark length widths for the 2T mark and 3T mark in this binarized signal are w2Tm and w3Tm [nsec].

である。なお、Σは測定区間内での総和を示す。 The average values calculated by repeatedly measuring the mark length widths w2Tm and w3Tm in the measurement section are W2Tm and W3Tm.
Here, if the number of 2T mark and 3T mark samples (number of appearances) in the measurement interval is N2Tm and N3Tm, the average values W2Tm and W3Tm are:

It is. Note that Σ represents the total sum in the measurement interval.

となる。Ｔはチャネルクロック周期[nsec]である。 Next, if the difference between the average values W2Tm and W3Tm and the ideal value of the mark length is ΔW2Tm and ΔW3Tm, respectively,

It becomes. T is the channel clock period [nsec].

とする。
この品質測定値Ｅｑが小さい値であるほど、２Ｔマーク幅・３Ｔマーク幅が理想値に近いと言える。 Using the difference values ΔW2Tm and ΔW3Tm from this ideal value, the quality measurement Eq is

And
It can be said that the smaller the quality measurement value Eq, the closer the 2T mark width and 3T mark width are to the ideal values.

Next, a calculation example of the reliability evaluation value Er will be described.
As shown in FIGS. 5 and 6, an example in which the reliability evaluation unit 22 includes a pattern-specific sample number integrator 24 c, an erroneous recognition rate calculation unit 24 d, and an evaluation value calculation unit 23 is used.

となる。但し、Ｎ2Tm、Ｎ3Tmは測定区間内での２Ｔマーク、３Ｔマークのサンプル数（出現回数）であり、Ｎ2Tm_ i、Ｎ3Tm_ iは、テスト記録に用いたテスト記録データパターン中に存在する２Ｔマーク、３Ｔマークの数である。
テスト記録データが固定データパターンである場合は、２Ｔマーク、３Ｔマークの存在数Ｎ2Tm_ i、Ｎ3Tm_ iは、予めわかっている。
テスト記録データがランダムデータパターンである場合は、２Ｔマーク、３Ｔマークとしての存在数Ｎ2Tm_ i、Ｎ3Tm_ iは、一般的な存在頻度から推定される値とすればよい。 In this case, as the reliability evaluation value of the decoding result for knowing whether or not the decoding is correctly performed, the number of samples for each pattern is measured, the pattern misrecognition rate is calculated, and the reliability evaluation is performed based on this misrecognition rate. The value Er is obtained.
The error recognition rates RN2Tm and RN3Tm of 2T mark and 3T mark in the measurement section are

It becomes. However, N2Tm and N3Tm are the number of samples (number of appearances) of 2T mark and 3T mark in the measurement section, and N2Tm_i and N3Tm_i are 2T mark and 3T existing in the test recording data pattern used for test recording. The number of marks.
When the test recording data is a fixed data pattern, 2T mark and 3T mark existence numbers N2Tm_i and N3Tm_i are known in advance.
When the test recording data is a random data pattern, the existence numbers N2Tm_i and N3Tm_i as 2T marks and 3T marks may be values estimated from general existence frequencies.

That is, when the 2T mark and the 3T mark appear when the test recording data is reproduced, the pattern-specific sample number integrator 24c counts each of the 2T mark and the 3T mark within the measurement interval. (Number of appearances) N2Tm and N3Tm are obtained.
Then, the misrecognition rate calculation unit 24d calculates the above (Expression 4) using the counted 2T mark and 3T mark sample numbers N2Tm and N3Tm and the original 2T mark and 3T mark existence numbers N2Tm_i and N3Tm_i. To obtain false recognition rates RN2Tm and RN3Tm.

この（数５）は、誤認識率ＲN2Tm、ＲN3Tmのうちの値の大きい方を信頼性評価値Ｅｒとするという意味である。
そしてこのように求められた信頼性評価値Ｅｒは、その値が小さい値であるほど、品質測定値の信頼性が高いと言えるものとなる。 Then, the evaluation value calculation unit 23 calculates the reliability evaluation value Er based on the erroneous recognition rates RN2Tm and RN3Tm. For example, the reliability evaluation value Er is calculated by the following (Equation 5).

This (Expression 5) means that the larger one of the erroneous recognition rates RN2Tm and RN3Tm is set as the reliability evaluation value Er.
And it can be said that the reliability evaluation value Er calculated | required in this way is so that the reliability of a quality measurement value is so high that the value is small.

For example, the quality measurement value Eq and the reliability evaluation value Er are obtained as described above.
In step F106 of FIG. 8, the optimum adjustment value is determined from the quality measurement value Eq and the reliability evaluation value Er obtained for each of the adjustment values P0 to P80.
For example, in this case, the adjustment value having the smallest quality measurement value Eq is selected as the best write strategy from the reproduction results of the test recording with 81 types of adjustment values (write strategy). However, at this time, those whose reliability evaluation value Er is equal to or greater than the threshold value Erth are excluded from the selection targets, so that the quality measurement values Eq that are inappropriate in the situation described with reference to FIG. 12C are excluded. To do. As a result, the adjustment value selected based on the quality measurement value Eq is correctly and optimally written. That is, the write strategy adjustment can be executed appropriately.

By performing the write strategy adjustment as described above in the present embodiment, the reliability of the write strategy adjustment in the disk drive device can be improved.
For example, when the quality of the initial strategy (the adjustment value P0) used as the starting point of the write strategy adjustment is very bad, the quality of the test recording performed for the adjustment is also very bad. For example, the mark length is erroneously decoded. The quality measurement value used as an evaluation index for the write strategy adjustment may not be acquired correctly due to the cause. As a result, in the past, erroneous strategy adjustment has been performed, but according to this example, such a disadvantage is caused by calculating the reliability evaluation value Er indicating the reliability of the quality measurement value Eq. As a result, the reliability of the write strategy adjustment can be improved.

As described above, specific examples have been described with the write strategy adjustment as an example in the embodiment, but the present invention can also be applied to applications other than the write strategy adjustment.
For example, in various automatic adjustments such as focus servo, tracking servo, tilt adjustment, and spherical aberration correction of an optical system, it is considered to use a jitter value or a reproduction signal amplitude value due to a reproduction data and a clock timing error as a quality measurement value Eq. In this case as well, it is effective to detect the reliability of the quality measurement value Eq using the reliability evaluation value Er.
Further, the present invention can be applied as a playback apparatus and adjustment method for various media other than the playback apparatus or recording / playback apparatus corresponding to the Blu-ray disc. For example, the present invention can be applied to playback devices and recording / playback devices such as various optical disks other than Blu-ray discs, magnetic disks, magneto-optical disks, and card media. ,

It is explanatory drawing of the structure concept of embodiment of this invention. It is explanatory drawing of the structural concept of the reliability evaluation part of embodiment. It is explanatory drawing of the structural example of the decoding result evaluation part of embodiment. It is explanatory drawing of the structural example of the decoding result evaluation part of embodiment. It is explanatory drawing of the structural example of the decoding result evaluation part of embodiment. It is explanatory drawing of the structure concept in the case of performing the write strategy adjustment of embodiment. 1 is a block diagram of a disk drive device according to an embodiment. It is a flowchart of write strategy adjustment of an embodiment. It is explanatory drawing of the write strategy adjustment value of embodiment. It is explanatory drawing of the mark length width used for calculation of the quality measurement value of embodiment. It is explanatory drawing of the write strategy adjustment parameter of embodiment. It is explanatory drawing of the example from which a quality measurement value becomes an incorrect value.

Explanation of symbols

  1 optical pickup, 4 matrix circuit, 5 A / D / PLL unit, 6 playback processing unit, 7 recording processing unit, 9 memory unit, 10 system controller, 13 laser driver, 14 write strategy unit, 20 quality evaluation unit, 21 quality Measurement value calculation unit, 22 Reliability evaluation unit, 23 Evaluation value calculation unit, 24 Decoding result evaluation unit, 24a SER calculation unit 21, 24b bER calculation unit, 24c Sample number integrator by pattern, 24d Error recognition rate calculation unit, 30 Head unit, 31 Data reproduction system circuit unit, 32 Data recording system circuit unit, 33 Control unit, 34 Test recording data generation unit

Claims (9)

A head unit for reading a signal from a recording medium on which information is recorded by rows of marks and spaces;
A data reproduction system circuit unit that performs reproduction processing on the signal read by the head unit and obtains reproduction data;
A quality measurement value calculation unit for calculating a quality measurement value indicating the quality of the signal read by the head unit;
A reliability evaluation unit for calculating a reliability evaluation value indicating the reliability of the quality measurement value;
A control unit that determines the quality of a signal obtained from the recording medium using the reliability evaluation value and the quality measurement value, and performs predetermined adjustment control based on the determination result;
A playback apparatus comprising: The reliability evaluation section
A decoding result evaluation unit for obtaining a decoding result evaluation value indicating reliability of the decoding result in the data reproduction system circuit unit;
An evaluation value calculation unit that calculates the reliability evaluation value using the decoding result evaluation value;
The playback apparatus according to claim 1, further comprising: The decryption result evaluation unit
The reproduction apparatus according to claim 2, wherein a symbol error rate obtained from an error correction processing result at the time of decoding in the data reproduction system circuit unit is used as the decoding result evaluation value. The decryption result evaluation unit
3. The reproducing apparatus according to claim 2, wherein a bit error rate obtained by judging whether the data obtained by the data reproducing system circuit unit is correct or not in bit units is used as the decoding result evaluation value. The decryption result evaluation unit
An error recognition rate in the data reproduction system circuit unit for a specific pattern is obtained as a pattern of information represented by the mark and space in the recording medium, and the error recognition rate is used as the decoding result evaluation value. The playback apparatus according to claim 2. The head unit can record information in a row of marks and spaces on the recording medium,
A data recording system circuit unit that applies a recording drive signal based on data to be recorded to the head unit to perform mark recording on the recording medium;
The reproducing apparatus according to claim 1, wherein the control unit performs adjustment control of the recording drive signal using the reliability evaluation value and the quality measurement value. The control unit
The test recording data is recorded on the recording medium by the data recording system circuit unit and the head unit while switching the adjustment value of the recording drive signal.
Test reproduction data recorded at each adjustment value is reproduced by the head unit and the data reproduction system circuit unit, and the reliability evaluation value and the quality measurement value obtained corresponding to each adjustment value are used. The reproduction apparatus according to claim 6, wherein adjustment control of the recording drive signal is performed. The head unit is an optical head unit that irradiates the recording medium with laser light to record and read information by a row of marks and spaces.
The data recording system circuit unit generates a laser driving pulse signal as the recording driving signal,
7. The reproducing apparatus according to claim 6, wherein the control unit performs adjustment control of edge timing of the laser driving pulse signal as the adjustment control. As a signal quality evaluation method of a reproducing apparatus for reproducing information on a recording medium on which information is recorded by a mark and space column,
Reading a signal from a recording medium on which information is recorded by a row of marks and spaces;
Calculating a quality measurement value indicative of the quality of the read signal;
Calculating a reliability evaluation value indicating the reliability of the quality measurement value;
Evaluating the quality of the signal read from the recording medium using the quality measurement value determined to be reliable by the reliability evaluation value;
A signal quality evaluation method comprising:

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